John Herlihy, Google’s VP of online sales, believes that the desktop has about three years before phones replace it. And he first made that prediction a year ago.

Previously, only those with BlackBerrys used phones for everything, including simple tasks such as email. Now, according to a new Nielsen smartphone report, 43% of mobile phone users have smartphones. People use phones to do things that used to be reserved for desktop PCs, such as surf the web, play games, and watch video.

In fact, a recent poll shows that 46% of Americans think tablets will replace laptops in the future. This is especially true among adults ages 30 to 64. Young adults (ages 18 to 29) and those older than 65 are a little more sceptical. Only roughly a third think that tablets will eventually eliminate the need for laptops, according to the polling group Poll Position.

We are already seeing the impact of smartphones and tablets. Analysts Gartner said shipments of laptops and desktops in the final quarter of last year were down 1.4% on the previous year and according to Bloomberg, The US personal-computer market declined for the first time in a decade last year, hurt by sluggish consumer spending, supply shortages, and the popularity of smartphones and tablets.

New Zealand’s Business Day reports that Apple is believed to have sold more than 35 million iPads last year. So the trend is clear to see and it’s not confined to one economic bloc. The Times of India reported that Smartphone sales set to double in 2012.

It’s that migration away from fixed to mobile devices that is behind the move, and a key part of that is the cloud, which allows documents to be created in one location on one device and accessed by another somewhere else. Underpinning that is increasingly faster and more widely available broadband.

According to research firm IDC, more internet users in the US will access the web through their mobile devices than through wireline devices by 2015. Smartphones and tablets are selling at unprecedented rates. As a result, the number of US mobile internet users is expected to experience a compound annual growth rate of 16.6% between 2010 and 2015. “Soon, more users will access the web using mobile devices than using PCs, and it’s going to make the internet a very different place,” says IDC research vice president Karsten Weide.

But could we then see a need emerge for a central mini-hub in offices and homes – a faster (and smaller) central server with vast data capacity to act as a virtual docking port, a sort of cloud halfway house, to control security and access rights, for example? Will we then see slave or dumb terminals being used on the back of that server as cheaper and simpler ways to access documents created elsewhere. Will we then see people sitting at desks with screens? Are we only half way round what could be an ever revolving circle!?